Electric road lighting has traditionally been provided through the use of high-intensity discharge lamps, often based on high-pressure sodium lamps. Such lamps are either centrally controlled, or controlled by local photosensitive sensors and are effectively either on or off. More recently new street lighting technologies have been introduced based on LEDs. Such lamps can offer a higher degree of control, and may be individually controlled in terms of brightness, wavelength of light used, etc.
Traditional street lighting is typically homogenous within a given area, and does not adapt to changing conditions or requirements within the area in the proximity of the lamp. However more recently, as well as providing illumination, so-called ‘smart streetlights’ may offer other functionality based on communication or sensor technology, such as the ability to track vehicles, communicate with other lights, vehicles or a central system. They may also contain intelligence to modify their operation based on events in their location.